The present invention relates to an acoustic fluid machine for a gas, the machine utilizing acoustic resonance-based fluctuations in pressure amplitude.
There is a known acoustic fluid machine in which a piston is reciprocated by an actuator at high speed axially with a very small amplitude is provided in a larger-diameter base of an acoustic resonator, and a gas is sucked into the acoustic resonator and discharged therefrom via the smaller-diameter upper end by virtue of pressure fluctuations within the acoustic resonator accompanying the reciprocation of the piston.
This acoustic fluid machine utilizes fluctuations in the pressure amplitude of standing acoustic waves generated by resonance of a gas column inside the tube accompanying movement of the piston when the piston reciprocates axially with a very small amplitude, and comprises as an operating part only an actuator that causes the piston in the base of the acoustic resonator to reciprocate at high speed.
The acoustic fluid machine has a very simple structure, has the advantage that the possibility of malfunction is very small, and is expected to find wide application in the future.
However, in the above-mentioned acoustic fluid machine, desired intake and discharge actions are carried out by transmitting to the upper end sound waves generated on the surface of the piston, which has minute high speed vibrations, and in order to achieve an effective action it is necessary to minimize the interference of sound waves that reach to the upper end.
In order to do this, it is necessary to maximize the ratio of the length of the acoustic resonator to the diameter of the piston. That is, in order to obtain specified intake and discharge abilities efficiently, it is necessary to increase above a specified level the length of the acoustic resonator relative to the diameter of the piston.
However, for a given intended performance, if the length of the acoustic resonator is too large, its application is restricted, and the cost of production and installation becomes high.